This section provides background information related to the present disclosure which is not necessarily prior art.
Sleeping bags come in several different physical configurations including, but not limited to, rectangular, semi-rectangular and mummy. In addition, some sleeping bags may incorporate an integral hood. Typically, sleeping bags have one or more closure devices, such as zippers, to provide access to an entrance aperture and which can be located on the sides, ends or top to permit use of the sleeping bag.
Sleeping bags typically include first and second opposed halves defining a sleeping compartment therebetween and which are connected in such a way to define the entrance aperture at an entrance side or end of the sleeping bag. Each half of the sleeping bag includes an outer shell layer and an inner shell layer with an insulating material disposed and retained between these two layers. Insulation thickness depends on the coefficient of thermal conductivity of the insulation material and the minimum ambient air temperature that is expected to be encountered by the user. However, regardless of the type of insulating material and its coefficient of thermal conductivity, colder ambient air temperatures require that a greater thickness of insulation be used to keep heat loss from the user sufficiently low enough that the user does not become uncomfortable within the sleeping compartment.
In view of the above, most sleeping bags having a “usable” ambient air temperature range within which the user will remain comfortable. However, to facilitate the use of otherwise conventional sleeping bags in colder ambient air temperature conditions below the lower limit of its usable temperature range, a need exists to develop alternatives for reducing heat loss within the sleeping compartment. The present disclosure is directed to addressing the above-noted shortcomings of conventional sleeping bags and to providing a solution for extending the lower limit of the useable temperature range of conventional sleeping bags.